The U.S. is facing a renewal of great power competition that requires its military to present "credible" options to civilian leaders that can be acted upon, the Air Force chief of staff said.

Gen. David Goldfein, speaking to reporters Tuesday on the sidelines of the Singapore Air Show, didn't mention any countries by name. But a recent Pentagon strategy report warned that America faces competition as China and Russia narrow their technological gap with the U.S. military and seek "to shape a world consistent with their authoritarian model."

"We are acknowledging the fact that we're back into great power competition, which in and of itself raises some of the risk level," Goldfein said. History shows that those "who have strategic partners win, and those that don't, lose."

"Our militaries have a responsibility to bring military options to our civilian leaders. And those options have to be credible, they have to be executable and we have to be able to articulate any risks associated with executing those options," he said. "It's all geared towards ensuring that our diplomats have what they need to negotiate a better peace."

Besides China's greater economic and military clout, the U.S. faces a more assertive North Korea, as Kim Jong Un accelerates his weapons programs, seeking a missile capable of hitting the continental U.S. with a nuclear warhead. That has led President Donald Trump to threaten a military strike against the regime in Pyongyang, even as some diplomats warn of potential catastrophic consequences on the Korean Peninsula from outright conflict.

Since coming to office, Trump has also spurred concerns among some U.S. allies in Asia, and some smaller states, over the future of the U.S. commitment to a region that has for decades looked to America for security assurances. That's as China pushes its claims to disputed maritime areas, including building military facilities on reclaimed reefs in the South China Sea.

The 11-page unclassified summary of the 2018 National Defense Strategy released last month warned that confronting China and Russia -- and staying ahead of their quickly expanding military capabilities -- are the Pentagon's "principal priorities." The two U.S. rivals are actively seeking to "co-opt or replace the free and open order that has enabled global security and prosperity since World War II," according to the report.

Without citing a country by name, Goldfein said it was appropriate to be critical of countries "pushing against the rules-based order."

Goldfein declined to comment on specifics of planned future deployments to the region, including whether the upgraded version of the U.S.'s largest non-nuclear bomb -- a 30,000-pound "bunker-buster" that can only be carried by the B-2 stealth bomber -- could be used against North Korea. Pyongyang's main nuclear test site is housed in a maze of tunnels under a mountain and other weaponry is suspected to be buried across the country.

"We want to be strategically predictable, but operationally unpredictable," he said. "So where we move forces, how we move forces, how we might execute, that is something we would never want to divulge to a competitor or an adversary."

"Our job in the military is to ensure our secretary of state, Secretary Tillerson, and his counterparts that are involved in negotiating forward in a pressure campaign, have got credible military options to back them up," he said, referring to Rex Tillerson.